Different polymers for various applications have been known for many decades in the prior art. Polyolefins, polyesters, polyamides, polyacrylates, or polycarbonates may be mentioned here by way of example. The selection of these different polymeric materials depends in general on the intended purpose and the desired mechanical properties, for example impact strength or heat resistance.
However, these polymeric materials are problematic in that the reactants used to prepare such polymers (for example terephthalic acid and isophthalic acid, used as aromatic building blocks for polyesters) come from synthetic sources. The biodegradability of the resulting polyesters is also insufficient. There is accordingly an immense demand in the marketplace for polymeric materials, especially polyesters, where reactants used for preparing the polyesters are essentially obtained from renewable raw materials, and the resulting polyesters are biodegradable. There has hitherto been no shortage of attempts to synthesize such polyesters from renewable raw materials. Examples include polylactide as well as polyesters based on furan-2,5-dicarboxylic acid.
WO 2010/077133 A1 discloses a process for preparing polymers obtained on the basis of 2,5-furandicarboxylic acid and diols/polyols. The process proposes a first step of forming a prepolymer (or “monomer”) from the aforementioned reactants and a subsequent, second step of conducting a polycondensation. With regard to the first step, WO 2010/077133 A1 proposes transesterifying a mixture of 2,5-furandicarboxylate with a diol. The transesterification is carried out using a tin catalyst. The polycondensation is proposed to be carried out under reduced pressure, again in the presence of a tin catalyst.
However, the attainable molecular weight and physical properties (for example, impact strength) of these prior art heteroaromatic polyesters, still fail to meet the expected standards of other prior art polyesters (for example, those formed from terephthalic acid and diols). Moreover, this process is only carried out in individual batches (“batchwise”) which generally result in varied product quality from batch to batch, resulting in an inhomogeneous mixed product obtained therefrom.